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Different spatial processing for
stimulus-centered and
body-centered representations
H. Ota, PhD; T. Fujii, MD, PhD; M. Tabuchi, MD, PhD; K. Sato, MSc; J. Saito, MD, PhD; and
A. Yamadori, MD, PhD

Abstract—The authors describe a patient who experienced two successive strokes in the right hemisphere. After the first
stroke, she showed stimulus-centered left neglect confined to right space on a circle discrimination task, which resolved.
After the second stroke, she showed body-centered left neglect on the same task. These observations of two types of left
neglect in the same patient suggest there are at least two distinct spatial attentional systems in the brain: global and focal
attentional systems.
NEUROLOGY 2003;60:1846 –1848

Unilateral spatial neglect (USN) is characterized by
a failure to notice stimuli presented in the contralesional space.1,2 According to the reference frame theory, left USN can be divided into body-centered left
neglect (BCLN)3,4 and stimulus-centered left neglect
(SCLN).5,6 BCLN is defined as less response toward
the left space of the trunk’s midsagittal plane compared with the right. SCLN is defined as failure to
notice the left side of a stimulus, irrespective of its
spatial location in relation to the body. Recently, we
confirmed the double dissociation of these two symptoms with one task,7 which suggests that spatial attention mechanisms operating with respect to the
body and with respect to a particular stimulus are
independent of each other. We herein report on a
patient who showed different manifestations of USN
after two successive strokes.
Case report. An 82-year-old, right-handed woman developed a
right cerebral infarction on January 11, 1999. Sensation of touch
was intact, but sensation of pain was mildly disturbed on the left
side. She showed a left homonymous hemianopia and left USN on
a line bisection task but not on a circle cancellation task.8 On a
double daisy copying task9 (daisy task), she failed to copy the left
side petals of both flowers, and more petals were omitted on the
right flower than on the left. On double simultaneous stimulation,
she showed extinction on the left to auditory and tactile stimuli. A
prosopagnosia was also present. An MRI revealed an infarction in
the right posterior cerebral artery (PCA) region (figure 1).

Five months after the first stroke, she again developed a right
cerebral infarction. She showed a left facial palsy and moderate
sensory disturbance of touch and pain on her left side, in addition
to the left homonymous hemianopia. She showed left USN on the
line bisection test and on the circle cancellation task. On the daisy
task, she neglected the left flower completely and copied the right
flower omitting petals on the left side. An MRI obtained 5 months
after the second stroke showed an infarction in the right middle
cerebral artery (MCA) region adjacent to the old lesion (figure 2).

Materials and methods. We used a circle discrimination task7
(CDT) to qualify and quantify the types and degree of USN. Stimuli were composed of three types of circles (15 mm in diameter):
left side missing circle, complete circle, and right side missing
circle. Twenty circles of each type were arranged in a pseudorandom manner on a sheet of paper (29.7 ⫻ 42 cm). Six trials were
given for one evaluation. Evaluations were performed during
month 3 and month 4 after the first stroke and month 2 after the
second stroke. The patient was seated at a desk and instructed to
circle every complete circle and to cross out every incomplete
circle. The stimulus sheet was placed on the desk at midsagittal
plane of the patient’s body. No restriction was imposed on movement of the head or eyes. When she finished a task, she was
encouraged to reconfirm that all the items were satisfactorily
checked. There was no time limit.
Failure to circle or cross out figures on the left side of a paper
was regarded as BCLN. Circling of a left side missing figure was
regarded as SCLN. To evaluate BCLN and SCLN, the number of
figures correctly circled or crossed out was calculated for space
and types of circle. We analyzed the data using two-way analysis
of variance (ANOVA) with the body-centered frame (left and right
space) and stimulus-centered frame (left side missing, complete,
and right side missing circle).

From the Division of Neuropsychology, Department of Disability Medicine (Drs. Ota, Fujii, Tabuchi, and Yamadori), Tohoku University Graduate School of
Medicine, Sendai; and Rehabilitation Service (K. Sato) and Neurology Service (Dr. Saito), Saito Hospital, Ishinomaki, Japan.
Supported in part by a grant to A.Yamadori for scientific research from the Ministry of Education, Science, and Culture of Japan (08279103), and by a grant
from the Japan Society for the Promotion of Science (JSPS-RFTF97L00202).
Received May 29, 2002. Address in final form February 13, 2003.
Address correspondence and reprint requests to Dr. Hisaaki Ota, Division of Occupational Therapy, Department of Rehabilitation, Nakamura Memorial
Hospital, Minami 1-jo Nishi 14-chome, Chuo-Ku, Sapporo 060-8570, Japan: e-mail: hisohlyon@hotmail.com
1846

Copyright © 2003 by AAN Enterprises, Inc.

Figure 1. Brain MRI (FLAIR) performed 1 month after the first stroke.
The lesion was located mainly in the
right cuneus, precuneus, lingual gyrus,
parahippocampal gyrus, lateral occipital gyri, and the pulvinar. The left sides
of the images depict the right side of the
brain.

Results. In the first evaluation, ANOVA revealed a main effect
of stimulus-centered frame [F(2,30) ⫽ 4.93; p ⬍ 0.05]. Post hoc
analysis using Fisher’s protected least significant difference
(PLSD) revealed that the number of correct responses for left side
missing circles (17.50 ⫾ 2.88) was fewer than for complete circles
(19.33 ⫾ 1.03; p ⬍ 0.05) and right side missing circles (19.67 ⫾
0.52; p ⬍ 0.01). Furthermore, there was an interaction between
these two factors [F(2,30) ⫽ 8.69; p ⬍ 0.005], indicating that there
was an effect for stimulus-centered frame on the right space
[F(2,15) ⫽ 9.42; p ⬍ 0.005]. Post hoc analysis using PLSD revealed the number of correct responses for left side missing circles
(7.67 ⫾ 1.86) was fewer than for complete circles (10.00 ⫾ 0.00;
p ⬍ 0.005) and right side missing circles (10.00 ⫾ 0.00; p ⬍ 0.005)
on the right space. In the second evaluation, the response for each
target was almost correct, and there was no significant difference.
In the third evaluation, ANOVA revealed a main effect for the bodycentered frame [F(1,30) ⫽ 1095.20; p ⬍ 0.001] but not for the

stimulus-centered frame. There were fewer responses for the left
space (1.17 ⫾ 1.60) than for the right space (25.83 ⫾ 2.14; figure 3).

Discussion. The patient experienced two cerebral
infarctions in 5 months, first in the right PCA region
and second in the right MCA region. After the first
stroke, our patient showed SCLN only in the right
space, but no BCLN was apparent on the CDT. This
symptom soon resolved itself. After the second
stroke, she developed BCLN, but no sign of SCLN
was apparent on the CDT. This interesting course of
events in terms of two types of left USN in the same
patient suggests there are at least two different spa-

Figure 2. Brain MRI (FLAIR) performed 5 months after the second
stroke. In addition to the old lesion, the
new lesion was located mainly in the
inferior parietal lobule, middle to the
posterior part of the superior and middle temporal lobe.

June (1 of 2) 2003

NEUROLOGY 60

1847

specific object would show rightward predilection
only in the right hemispace. A case report, which
showed left USN after a stroke in the PCA region,
manifested a similar set of symptoms to those of our
patient.10 This case and ours suggest that the focal
attentional function in the PCA region is different
from that in the MCA region. The disappearance of
the symptom after the first episode may have been
accomplished either by compensational decrease of
the stronger rightward attention of the left hemisphere or by increase of the weakened leftward attention of the right hemisphere.
In the second stroke, the lesion extended laterally
from the old lesion into the MCA region. This lesion
may have destroyed the global attention system in
the right hemisphere. Thus, our patient showed
BCLN on the daisy task and the CDT. Because of the
functional compensation of the focal attentional system after the first stroke, she may have been able to
judge each stimulus in the right hemispace on the
CDT. More clinical data are required to confirm our
hypothesis.
References

Figure 3. Mean number of correct responses for three
types of stimuli in the left and right hemispaces: the first
evaluation (A) and the third evaluation (B). Gray columns
represent mean number of correct responses for circles that
had a missing portion on their left side; black columns are
for complete circles; and white columns are for circles that
had a missing portion on their right side. The lines above
each column represent the SD of the mean.

tial attentional systems in the brain, i.e., global and
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In the first evaluation, the patient’s SCLN was
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toward the left, its distribution would be weakened
but become symmetric to both sides. Because the
focal attentional distribution of the left hemisphere
remains biased toward the right, attention toward a

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June (1 of 2) 2003

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